Lapping stone PETROGRAD, gabbro-diabase, 200*70*20mm
Lapping stone from gabbro diabase. Used for lapping the soles of planes, abrasive stones and other surfaces. It has a perfectly smooth surface. Lapping is carried out with abrasive powders or diamond pastes. Approximate dimensions: 200x70x20 mm. Made in Russia.
Gabbro diabase is a fine-grained full-crystalline volcanic rock, which in its chemical and mineral composition is quite close to basalt and most often has a black color. A characteristic feature of this stone is high hardness and considerable compressive strength. One of the distinguishing features of this natural stone is the relatively low content of silica in it (about 45-52%). The color of the mineral may be different. There are samples that are black, dark gray and even greenish-black color. The stone has a diabase (it is also called an ophitic) structure, which is formed by randomly located and elongated crystals of plagioclase, the whole space between which is occupied by augite.
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